The ion implanting method as one of the methods of introducing atoms or molecules into a target material is used in the manufacturing of a semiconductor device, and the reforming of a metal surface, and others. For example, in the manufacturing of a semiconductor device, the ion implanting method is used for imparting electrical conductivity to a polysilicon film comprising a gate electrode of MOSFET, or forming an n-type or p-type source/drain diffusion regions of MOSFET, or the like.
The ion implantation apparatus has an ion source for generating ions, an extraction electrode for extracting ions from the ion source, a separation magnet for separating the ions coming out from the ion source every mass, a lens for converging given ion species out of the separated ion species, and a wafer stage for loading thereon a wafer as the target material. The separation magnet is also called a mass analyzing magnet.
The ion implantation apparatus including such elements has different features of controlling ion-implantation angle to a wafer, or enhancing an efficiency of the ion implantation, and the like.
For example, it is known that a measuring mechanism of center-of-gravity for measuring a gravity center of the ion beam passed through the separation magnet is arranged to be able to move into and from the middle of the ion beam course, and further an angle of the wafer stage is controlled such that the irradiation direction of the ion beam measured by the center-of-gravity measuring mechanism coincides with a normal direction of the wafer.
It is known that, in order to control the ion implantation angle to the wafer, a regulating deflecting force means for regulating a deflecting force of the mass analyzing magnet is provided in the ion implantation apparatus, and further a wafer moving mechanism for moving the wafer along its surface direction is provided in the ion implantation apparatus.
Further, it is known that a mask for receiving the ion beam is provided between the ion source and the periphery of the mass analyzing magnet, then a value of a beam electric current passing through the mask is measured, and then a distance between an extraction electrode and the ion source is controlled such that the beam electric current is maximized.
Still further, it is known that values of electric currents of the ion beams with the exception of a specific mass, in plural types of ion beams separated by the mass analyzing magnet, are measured by the Faraday cup, and then an electric current of the ion beam with the specific mass is calculated indirectly based on the measured values. Thus, the electric current of the ions with the specific mass is measured while implanting the ions with the specific mass into the subject.
In this case, the Faraday cup may be arranged in the area located near a beam extracting port of the mass analyzing magnet, and then be fitted movably in the direction that intersects substantially orthogonally on the ion beam.
By the way, in the above technologies, from viewpoints of a size and a structure of a driving portion for driving the wafer stage, it is difficult that both a wafer turning mechanism and a normal angle-of-the-wafer changing mechanism are provided together.
Meanwhile, when the ion implantation angle is controlled on the condition that the ion species move to depict the ideal trajectory in the mass analyzing magnet, it is difficult to control an incident angle of the ion beam to the wafer with good precision by only regulating the magnitude of the deflecting force of the mass analyzing magnet.
Further, when used a method of connecting an ammeter to a target of the ion beam and then detecting a maximum value of the electric current of the ion beam, it is unfeasible to detect the incident position of the ion beam. Thus, it is difficult to control an incident angle of the ion beam.